#include "zgl.h"

int glRenderMode(int mode) {
  GLContext* c = gl_get_context();
  int result = 0;

  switch (c->render_mode) {
    case GL_RENDER:
      break;
    case GL_SELECT:
      if (c->select_overflow) {
        result = -c->select_hits;
      } else {
        result = c->select_hits;
      }
      c->select_overflow = 0;
      c->select_ptr = c->select_buffer;
      c->name_stack_size = 0;
      break;
    default:
      assert(0);
  }
  switch (mode) {
    case GL_RENDER:
      c->render_mode = GL_RENDER;
      break;
    case GL_SELECT:
      c->render_mode = GL_SELECT;
      assert(c->select_buffer != NULL);
      c->select_ptr = c->select_buffer;
      c->select_hits = 0;
      c->select_overflow = 0;
      c->select_hit = NULL;
      break;
    default:
      assert(0);
  }
  return result;
}

void glSelectBuffer(int size, unsigned int* buf) {
  GLContext* c = gl_get_context();

  assert(c->render_mode != GL_SELECT);

  c->select_buffer = buf;
  c->select_size = size;
}

void glopInitNames(GLContext* c, GLParam* p) {
  if (c->render_mode == GL_SELECT) {
    c->name_stack_size = 0;
    c->select_hit = NULL;
  }
}

void glopPushName(GLContext* c, GLParam* p) {
  if (c->render_mode == GL_SELECT) {
    assert(c->name_stack_size < MAX_NAME_STACK_DEPTH);
    c->name_stack[c->name_stack_size++] = p[1].i;
    c->select_hit = NULL;
  }
}

void glopPopName(GLContext* c, GLParam* p) {
  if (c->render_mode == GL_SELECT) {
    assert(c->name_stack_size > 0);
    c->name_stack_size--;
    c->select_hit = NULL;
  }
}

void glopLoadName(GLContext* c, GLParam* p) {
  if (c->render_mode == GL_SELECT) {
    assert(c->name_stack_size > 0);
    c->name_stack[c->name_stack_size - 1] = p[1].i;
    c->select_hit = NULL;
  }
}

void gl_add_select(GLContext* c, unsigned int zmin, unsigned int zmax) {
  unsigned int* ptr;
  int n, i;

  if (!c->select_overflow) {
    if (c->select_hit == NULL) {
      n = c->name_stack_size;
      if ((c->select_ptr - c->select_buffer + 3 + n) > c->select_size) {
        c->select_overflow = 1;
      } else {
        ptr = c->select_ptr;
        c->select_hit = ptr;
        *ptr++ = c->name_stack_size;
        *ptr++ = zmin;
        *ptr++ = zmax;
        for (i = 0; i < n; i++) *ptr++ = c->name_stack[i];
        c->select_ptr = ptr;
        c->select_hits++;
      }
    } else {
      if (zmin < c->select_hit[1]) c->select_hit[1] = zmin;
      if (zmax > c->select_hit[2]) c->select_hit[2] = zmax;
    }
  }
}
